Protein-targeted aptamers in liquid biopsy: from efficient screening to precise cancer diagnosis

Abstract

Early and precise cancer diagnosis is a substantial way to improve patient survival. However, the heterogeneity of cancer and the challenges associated with sampling tissues from concealed anatomical sites hinder reliable diagnosis using conventional clinical approaches. Leveraging noninvasive sampling and real-time molecular analysis, liquid biopsy offers new opportunities for individualized cancer diagnostics. Although circulating tumor cells (CTCs) and extracellular vesicles (EVs) carry key molecular information, the effective isolation and detection of these rare circulating biomarkers remain technically demanding. Aptamers, which are initially evolved by an in vitro optimized process termed systematic evolution of ligands by exponential enrichment (SELEX), refer to a special category of single-stranded functional oligonucleotides for specific recognition of targets by folding into unique tertiary structures. Benefiting from the flexible design, low immunogenicity, chemical/thermos stability, as well as modification convenience compared to conventional antibodies, aptamers are widely applied in liquid biopsy for accurate cancer diagnosis in molecular medicine. In this feature article, we review booming methods for detecting biomarkers of liquid biopsy, e.g., CTCs and EVs, based on aptamers which are screened by multitudinous methods of protein-targeting SELEX technologies. By itemizing our contribution to cancer-associated liquid biopsy using SELEX technique, we present our visions of the promising application of aptamers in accurate cancer diagnosis.